In the beginning, it is easy. When a fresh batch of Year 7s arrive in September, they are perfect. They look smart, they sit in silence - they even do their homework. They are scared. But now, halfway through the academic year, we heads of Year 7 begin to see the cracks appearing...

1. “Tuck that shirt in!”
   Boys’ shirts have long since parted company with their waistbands and the girls’ skirts have become shorter than your increasingly frayed temper. They wear these indiscretions with as much swagger as short, year 7 legs will enable. 
   
   
   
   
    
2. Mobile phones are appearing like molehills on the rugby pitch
   Of course, they were always there, on silent and communicating into the void of a school bag. But suddenly, Snapchat invades your lesson with the bleeps of notifications and the sniggers of brazenly read messages. And the more irritated you get, the funnier they find it. Hang on, did he just take a picture of me?  
   
   
   
   
    
3. School bags aren’t cool, ok? 
   Those brand new super practical rucksacks bought last August? Ditched. And for what? An unserviceably small shoulder bag, or worse, a pocket, prompting increasingly frequent requests to borrow textbooks, paper and even the most essential piece of school equipment… a pen. 
   
   
   
   
    
4. They’ve suddenly discovered make-up
   What did the girls of Year 7 get for Christmas? Just look at their faces: the make-up counter of Boots has been well and truly plundered. You now find a frightening amount of your time is spent handing out make-up wipes and reciting the school make-up policy. It becomes so automatic that you find yourself handing a wipe to the deputy head and lecturing her on her eye liner. 
   
   
   
   
    
5. Detentions hold no fear
   There was time that handing a Year 7 a detention was an event. They would tremble. Pledge to be better. Now? They take your punishment like it’s a commendation. And it is at this point you realise that they have well and truly settled in.
   
   
   

Howard Bunce was talking to Nicola Davison. He is Head of Year 7 at a Hertfordshire secondary school. When he’s not wielding make-up wipes, he teaches geography